Pituitary Macroadenoma: A Case of Balanced Deficiencies

Abstract Introduction: Diabetes insipidus (DI) rarely occurs in pituitary tumors although some patients may develop DI following tumor resection. However is known to occur with metastatic the or infiltrative disorders of gland. We are reporting a patient 2 cm macroadenoma whose was unmasked by glucocorticoid therapy. Case Presentation: A 61-year-old male history non-functioning macroadenoma, incidentally discovered on imaging 2015 and stable at 1.6cm for 4 years, referred endocrinology interval enlargement his macroadenoma. He had presented primary care due new headache during extreme physical exertion, but otherwise denied any symptoms such as vision loss, fatigue, decreased libido, weight urinary frequency. Repeat MRI indicated growth 2.1cm suprasellar component, no cavernous sinus involvement, abutting optic chiasm. Laboratory results revealed onset central hypothyroidism (FT4 0.21 ng/dL (ref 0.78-2.19) triiodothyronine 68 80-200) TSH 1.61 mIU/L 0.47-4.68), hypogonadism (Testosterone Free 1.3 pg/mL 6.6-18.1)) concern adrenal insufficiency cortisol 4.4 mcg/dL. empirically started hydrocortisone replacement until an ACTH stimulation test could be completed, after 3 days instructed begin low dose levothyroxine replacement. At close followup, that he developed hourly nocturia causing significant distress. An overnight water deprivation yielded serum sodium 152 mmol/L urine osmolality 191 mOsm/kg, both rapidly improving intravenous desmopressin. Copeptin 4.6 pmol/L. Discussion occurring including macroadenomas extremely rare. Secretion AVP hypothalamic osmoreceptors, supraoptic paraventricular nuclei, superior portion supraopticohypophyseal tract. deficiency most commonly damage these areas either through neurosurgery trauma, more disease. However, thyroid each precipitate development diabetes insipidus. Well described literature, independently impairs free excretion. Low stimulates release antidiuretic hormone, this secretion then inhibited exogenous steroid Cortisol interferes signaling unclear mechanisms V2 receptor post-receptor level, decreasing translocation type aquaporins therefore reducing reabsorption. It important recognize CDI can hormone